Brake disc mounting arrangement

ABSTRACT

An arrangement and method for mounting a brake disc to an axle hub of a vehicle is provided. The arrangement includes wedge-shaped holes at an radially inner region of the brake disc, corresponding wedge-shaped key inserts, a retaining device such as a retaining ring, and mounting devices such as bolts or studs and nuts that pass through the retaining ring and keys to bias the keys against the axle hub. The circumferential sides of the wedge shapes are aligned with radial lines extending from the rotation axis of the axle hub. This arrangement and method provides a simple, robust and easily installed brake disc mounting that minimizes heat transfer between the brake disc and the axle hub and accommodates thermal expansion of the brake disc and the axle hub to minimize thermal expansion-induced stresses to the brake disc.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to disc brakes for vehicles, and inparticular to an arrangement for connecting and securing a brake disc toan axle hub, including axle hubs utilized on commercial vehicles such astractor-trailer trucks, box trucks, buses, and the like. The inventionalso relates to a method for installation of a brake disc on an axlehub.

Disc brakes are increasingly being used on commercial vehicles,replacing conventional drum brakes. Very high braking energy isgenerated when the disc brake's caliper applies the brake pads to thebrake disc to slow such heavy vehicles. In order to deal with suchloads, very robust and often complicated designs have been required toconnect the brake disc of a disc brake to an axle hub to transfer thebraking forces from the brake disc to the hub. The design of the brakedisc-to-hub connection is further complicated by the heat generatedduring braking as the kinetic energy of the vehicle is converted intoheat energy by application of the brake pads to the brake disc. The heatthe hub receives from the brake disc can be detrimental to the axle huband its components (such as bearings and seals), as well as causing highcomponent stresses due to differences in thermal expansion betweendifferent materials (for example, between an aluminum hub and a steelbrake disc). The high heat can also cause brake fade and contribute topremature failure of braking components.

Commercial vehicle brake discs, also referred to as “brake rotors” or“rotors,” often are mounted onto axle hubs using so-called splinearrangements using a fixed or floating connection, such as taught inU.S. Pat. Nos. 6,626,273 and 7,410,036. One example a semi-floatingconnection is the Splined Disc® brake assembly from Bendix SpicerFoundation Brake LLC. These types of brakes typically are mounted on anaxle hub having a plurality of axially-oriented splines arranged aroundan outer circumference of a disc-mounting region of the hub. The brakedisc has corresponding radially-inward facing tabs about the innercircumference of the brake disc. The disc is mounted to the axle hub byaxially sliding the brake disc onto the hub's mating splines, followedby insertion and/or attachment of a variety of fasteners, brackets,etc., as necessary per the particular splined disc's design in order tosecure the brake disc against axial movement off of the hub. When somounted, the brake disc's tabs engage the hub's splines in a mannerwhich permits the very large braking forces generated by the disc braketo be transferred to the axle hub and hence to the axle to slow thevehicle. This often requires costly precision machining of thespline/tab engagement surfaces.

Splined discs typically have had substantial metal-to-metal contactbetween the inner radial tabs of the brake disc and either the faces ofthe axle hub splines or intermediary inserts that are used to transferthe braking loads from the disc tabs to the hub splines. Theintermediate inserts are used in conjunction with hub axial stop toaxially restrain the brake disc on the axle hub. This metal-to-metalcontact has the disadvantage of facilitating transfer of a large amountof brake heat from the brake disc directly to the axle hub. This is aparticular problem where the axle hub is formed from aluminum, amaterial which is being more frequently used for axle hubs in order tominimize vehicle weight and improve fuel economy, both because thematerial properties of aluminum (e.g., strength) are known to degrade athigher temperatures, and because the aluminum of the axle hub and thematerial of the brake disc (typically cast iron) can have significantlydifferent thermal expansion coefficients.

Other brake disc mounting arrangements are known which fix the brakedisc to a hub or only allow limited relative movement between the brakedisc and the hub. Such arrangements can inhibit the radial expansion ofthe brake disc, hub and connecting elements, leading to problems such asbrake disc deformation (for example, “coning” of the brake disc, inwhich the friction surfaces of the brake disc bend out of a planeperpendicular to the axle hub's rotation axis). Such deformations candecrease brake disc and brake pad life, and cause brake disc “cracking”due to deformation-induced tensile stress.

Prior art brake disc mounting approaches have also had the problem ofrequiring complex and costly assemblies of shims and/or springs at thehub/disc interface to flexibly take up component clearances providedbetween the brake components to accommodate differential thermalexpansion and wear- and noise-inducing vibrations. Further, the need toprovide disc-to-hub joints that are robust enough to be able towithstand very high temperatures during braking events and metal fatigueover the extended life of a brake disc has required the use of brakediscs with undesirably high mass and/or complexity and cost, such as theforming (typically by casting) of a tough material such as ductile ironover the grey iron of the brake disc in the hub region of the disc.

There exists a need for a brake disc mounting arrangement whichsubstantially reduces or eliminates altogether the need for complex shimand or spring assemblies, is simple to assemble, can withstand high heatloads with as low a thermal mass as possible, resists brake discdeformation and uneven brake disc and brake pad wear due to differentialheat-generated disc coning, is able to accommodate free radial thermalexpansion with little or no binding between the brake disc and hub, andprovides a fatigue life which exceeds the design life of the brake disc.

In order to address these and other problems with brake disc mounting inthe prior art, the present invention provides a brake disc having a hubregion geometry which accommodates differential radial growth of theaxle hub and the brake disc, minimizes the number of, or eliminatesentirely, the need for individual intermediary disc-to-hub elements, issimple to assemble and disassemble during installation and/orreplacement of the brake disc, minimizes the impacts of torsionalvibrations without the need for an additional vibration dampingmechanism, and is cost effective.

In one embodiment of the invention a brake disc is provided with aplurality of transverse wedge-shaped slots about an inner circumferenceof the brake disc which are formed with a specific geometry whichsubstantially reduces the stresses in the radially-inward-facing discteeth between the wedge-shaped slots.

The brake disc slots are radially positioned in locations correspondingto brake disc mounting studs provided on an axle hub. The brake disc andthe hub are connected to one another by wedge-shaped elements (aka“keys”) that are positioned in corresponding transverse wedge-shapedslots or holes in a radially inner region of the brake disc, preferablywith a retaining device that captures the portions of the brake discbetween adjacent keys against axial movement away from the axle hub. Thebrake disc's wedge-shaped slots may be open on the radially inward sideof the slot, or may be closed on the radially inward side, forminggenerally key-shaped holes at the inner radius of the brake disc.

The keys are provided with an aperture that can pass over a respectivebrake disc mounting stud, and with side surfaces that conform to theinner surfaces of the wedge-shaped brake disc holes. The keys may beformed from any material that can withstand the forces and temperaturesencountered during braking events in this region of the hub and brakedisc, and preferably from a material which is corrosion-resistant in theharsh environment of an axle hub.

Preferably, the contact surfaces between the lateral sides of the keysand the lateral sides of the wedge-shaped slots are sized large enoughthat, given the selected key and brake disc materials, contact surfacedeformation and wear are minimized to the point that intermediate shims,springs or other contact surface-protecting devices are not needed,i.e., such that the materials and geometry of the keys and the brakedisc permit direct key-to-wedge-shaped slot contact without intermediatedevices such as spacers and/or spring elements while still providing along service life without premature wear or damage to the key and slotcontact surfaces. The precise design of the geometry of thecomplementary keys and wedge-shaped slots also permits elimination ofthe use of intermediate vibration damping devices between the keys andthe wedge-shaped slots, as the inherent rigidity of the presentinvention's “gap-driven design” ensures the resonance frequency of theassembly is relatively high (for example, above 200 Hz) and thereforeout of the range of the natural frequencies of the vehicle's wheel-endcomponents (natural frequency being a function of mass and stiffness ofthe components).

Preferably the sides of the wedge-shaped keys and their respective brakedisc holes have their circumferential sides (the sides between theirradially inner and radially outer sides that are approximately parallelto the hub rotation axis), generally aligned in the direction of radiiextending from the hub rotation axis. Arranging the key and hole sidesin this manner facilitates cooperative movement of the keys in theirholes during simultaneous thermal expansion of the hub and the brakedisc, thereby minimizing the potential for jamming between the keys andthe brake disc and resulting thermally-induced stresses in the hub/discsystem. Other geometries are possible as the wedge geometry is afunction of the thermal mass of the rotor (the heat source) and the vanestructure (dissipating heat).

Preferably, the sides of the wedge-shaped slots and the keys arearranged with an angle relative to the radii in the range of 12° to 20°,more preferably 16°. As compared to conventional brake discs withparallel slot sides (aka “straight teeth”), a brake disc having slotside angles in the preferable range surprisingly has a stressdistribution around the circumference of the disc's inner hub attachmentregion during it braking event which is substantially more equallydistributed between the inward-projecting disc teeth than in a brakedisc with straight teeth.

It is known in the art that when brake pads are applied to a brake discduring a braking event, the pad's clamping forces are applied over alimited arc of the friction surfaces of the disc. As a result, theamount of the braking load sustained by the individual teeth varies withthe number and circumferential position of the teeth about the hub. Forexample, in a brake disc with ten straight teeth, the tooth carrying thehighest load may be carrying 10 times as much load as adiagonally-opposite tooth. A brake disc with ten wedge-shaped slots inthe preferred slot-side angle range instead may see maximum-to-minimumload difference ratios of less than 3:1. The much more even sharing ofthe braking force loading among the brake disc mounting interface hasseveral benefits, including lower maximum stress levels, reduced contactsurface wear and longer component life, and the ability to designsmaller brake disc interfaces which have less contact area for heattransfer from the brake disc to the hub.

Preferably, the keys are sized in the axial direction such that they arefirmly biased against the hub at all times. The holes in keys throughwhich fasteners pass preferably are sized near the size of the outerdiameter of the fastener in order to maximize the load-bearing surfacecontact between the keys and the fasteners.

The present brake disc mounting arrangement is particularly simple andeasy to install and/or replace. An embodiment of a method ofinstallation includes locating a brake disc on an axle hub with thebrake disc's wedge-shaped holes aligned with the hub's mounting studs orfastener-receiving holes, inserting corresponding wedge-shaped keys intothe brake disc's wedge-shaped holes, placing a bolting ring over thekeys, and installing fasteners that bias the keys against the hub. Thekeys allow the rotor to be piloted on the hub. Other variations arepossible, for example, the keys may be located in the brake disc holesbefore the brake disc is located on the axle hub, or the fasteners maybe fed through the keys before the keys are located in their respectivebrake disc holes.

The present invention further has the commercially significant advantageof providing the ability to readily adapt different brake disc designsfrom various brake component manufacturers to mount the brake discs onany standard flat-faced axle hub from various axle hub manufacturers.

There are multiple axle hub designs in the market, each with anassociated component for supporting a brake caliper known as a “torqueplate.” The torque plate typically defines, in a restrictive manner, thelocation of the brake caliper and its carrier relative to the hub. Thebrake caliper and carrier design in turn defines the axial location ofthe brake disc rotor, which must be located between the brake pads onwhich the brake caliper's brake applications devices act to apply thebrake. The axial location of the brake disc can be a critical parameter.The tight clearances in a commercial vehicle wheel hub region raisesconcerns for maintaining adequate clearance to wheel valve stems toavoid impacts which could shear off a valve stem and cause sudden tiredeflation. The tight spaces also raise concerns with the brake actuatornot being misaligned to the point of hitting the frame and accidentlyreleasing a parking brake.

Due to the variety in proprietary brake component designs, there is no“universal” brake disc in the commercial vehicle market which may bemounted directly to all, or even most, axle hubs (due to, for example,different bolt patterns) and which will be assured of being in thecorrect axial location for caliper fitment in different brake designs.

The present invention provides the opportunity to provide a brake discmounting arrangement compatible with a universal or near-universal brakedisc by providing appropriately-dimensioned key rings that correctlymate a brake disc with the present invention's key-receiving slots witha particular combination of axle hub and brake caliper designs. Forexample, in many applications one or more manufacturers may supplycomponents for a wheel end that includes a particular model of an axlehub, a particular model of a torque plate, a particular model of a brakecaliper, and a particular model of a brake disc with a mounting fastenerpattern and axial offset to suit that unique combination of components.When it is time to replace the brake disc, rather than being required touse a proprietary brake disc, the a standardized (and thus lower cost)brake disc with an appropriate key-receiving slot arrangements may beadapted to the particular brake application. Such a standardized brakedisc may be mounted to the particular axle hub using an intermediate keyring adapter that is dimensioned with mounting pattern that iscompatible with the particular hub's mounting stud pattern (i.e., aparticular pattern of stud holes at a particular mounting hole ringradius). The associated key ring would be provided with an appropriatethickness to ensure the standardized brake disc is properly axiallyaligned with the particular model of brake caliper (which in turn isaxially located by the particular model of torque plate). The axialoffset of the brake disc from the face of the particular model of axlehub may be readily set by making the key ring's webs between adjacentkeys the appropriate thickness that results in the brake disc beingcorrectly positioned between the caliper's brake pads when the brakedisc abutting the key ring webs. In other embodiments, the brake discand/or the key ring webs may be provided with more than one axialheight, such that by rotation of the brake disc relative to the ringduring installation, different axial positions of the brake discrelative to the torque plate may be obtained.

In the prior art there are known to be hundreds of combinations oftorque plate, hub, brake caliper and brake rotors and associatedoffsets. The use of a limited number of standardized brake discs withappropriate key ring adapters would enable significant cost savings fromsimplified and more efficient brake disc manufacture (lower toolingcosts and cost efficiencies from greater production volume as comparedto more limited production of individual proprietary brake discdesigns), simplified product logistics (fewer part numbers to administerand maintain in inventory, and greater availability to immediatelyfulfill a parts order); and simplified and less costly service needs(less technician time to determine what parts are required for aparticular brake service and to complete the service).

Preferably, the key ring is formed from a powdered metal, which offersseveral advantages over aluminum and other materials such as steelalloys.

This approach reflects a substantial departure from the prior art.

In the prior art the conventional wisdom has been that costly materialswith higher elongation and higher yield strength properties had to beused in an application such as the present invention, in order toincrease fatigue life and otherwise provide sufficient resilience tosurvive the high temperature, high vibration, high applied forceenvironment of a commercial vehicle disc brake.

Counter to this conventional belief, the inventors have deliberatelyselected a more brittle material with a low range of elongation,applying the material in a highly targeted manner, such as varying thepowdered metal's density in different regions of a key ring to providehigher strength only in regions where needed. The use of a more brittlematerial is further aided in applications with the above-describedkey-and-slot arrangements, as the lower peak stresses experienced by thebrake disc during a braking event provides additional design margin,i.e., lowers the stress levels the powdered metal must be able towithstand.

Powdered metal component properties are highly dependent on the processand equipment used to form the component, where the properties of thematerial of the component are functions of surface area, press force,material alloy composition, and the combination of the shaping of thecomponent mold and the distribution of the powdered metal within themold prior to compacting. For example, when a powdered metal alloycomposition of FLC-4805-100HT per MPIF Standard 35 is subjected tocompression in a 750 ton press, a targeted density on the order of 7grams/cm³ may be obtained in a key ring with a surface area of 115 cm².In a specific example of a particular key ring (i.e., without limitingthe present invention to the specific numerical values that follow), thepowdered metal may have a targeted range of material densities on theorder 6.9 gr/cm³-7.2 gr/cm³, with the density made higher in criticalareas, such as at a radius between a key and inter-key web (i.e., in astress concentration region). At a post-formation density of 6.8-7.0gr/cm³, the local yield strength will be on the order of 725-760 MPa inthe high-stress root region, which is substantially higher that themaximum loading expected in this particular key ring (560 MPa).

The use of variable-density powdered metal as a brake disc-to-axle hubadapter material provides many advantages, and frees designers from theprior art's material constraints. With targeted powdered metal design,designers may now develop adapter designs in which the engineeringrequirements (e.g., strength, fatigue life, fracture toughness) can bemet while meeting other priority demands such as lower cost and weight.

A powdered metal key ring in accordance with the present invention canbe expected to be lighter than a key ring formed from a steel alloy thatcan meet the same strength requirements. This represents the potentialfor substantial savings in weight at each axle end (contributing toimproved fuel economy and consequently lower emissions), as well assavings in cost from avoiding use of high-cost alloy steel materials anddifficult machining operations.

The powdered metal key ring of the present invention also avoids theproblems of some conventional lighter-weight materials. For example, itis well known that at higher temperatures (temperatures obtainable in aheavy braking environment) aluminum loses a significant portion of itsstrength. As a result, components formed from aluminum must be designedaccordingly, which typically resulting in much larger components tolower the local stresses to a survivable range (and thereby negatingmuch of aluminum's weight advantage). In contrast, powdered metal'smaterial properties are significantly less temperature dependent overlarge temperature ranges; indeed, powdered metal sintering temperaturesare far above any temperature likely to encountered in a brakingenvironment. Powdered metal components may also be designed to besubstantially smaller than corresponding aluminum components, aspowdered metal is typically on the order of five times stronger thanaluminum.

From a thermal isolation standpoint, a powdered metal key ring mayprovide further “downstream” benefits. For example, because powderedmetal is a good thermal isolator, the amount of heat transferred fromthe brake disc to the axle hub through the key ring may be lower thanthe amount of heat that would be otherwise transferred in a conventionalbrake disc mounting arrangement. This in turn may translate into theability to use aluminum as the axle hub material in place of heavy ironor costly steel, because the aluminum hub would be less likely to seetemperatures high enough to unacceptably reduce the strength of thealuminum. A further benefit may be significantly reduced temperatures atthe bearings on which the hub rotates.

The benefits of the thermal isolation capabilities of a powdered metalbrake disc key ring adapter are exemplified by a comparison with priorart brake disc designs. In the prior art, in order to preventtemperatures in the material of a flat-faced axle hub from exceedingdesign limits, a common solution was the so-called “U-shaped” brakedisc, i.e., a brake disc having friction discs (the region of thehighest temperature during a braking event) that are held axially wellaway from the face of the axle hub by a “hat” or bucket-shaped flangesection (in cross-section, U-shaped sections). To the knowledge of theinventors, the use of a key ring adapter formed from variable-densitypowdered metal, particularly use such an adapter with thestress-equalizing geometries discussed above, has resulted in the firstpractical, cost-efficient design that can provide thermal isolationcomparable to a U-shaped brake disc. In one example, the present keyring adapter approach resulted in temperatures at the bearings of anaxle hub on the order of 50° C., well below a design target of 60° C.,and far below the temperatures on the order of 80-90° C. with a priorflat rotor attachment approach.

Powdered metal also has advantages in lower cost and simpler componentmanufacturing operations. Powdered metal components are formed in “netshape” or “near net-shape” processes, primarily by high-pressure, andoptionally high temperature, pressing in molds. When the components areremoved from the molds they are in a near-finished state, thus avoidingcostly, intricate machining such as that required of raw, unfinishedforged component cores.

The powdered metal key ring in accordance with the present inventionalso provides related advantages during initial installation andsubsequent replacement of brake discs. A large fraction of the prior artbrake disc mounting arrangements require the use of additional smallparts, from simple to complex combinations, to secure and/or preventtransfer of vibration energy between the brake disc and the axle hub andvice-versa. These spring and/or shim components add cost to the brakedesign, and require additional technician effort and time (with itsrelated labor costs) to complete disassembly and reassembly of thesecomponents during a brake disc replacement job. All of this costlyhardware and labor is eliminated by present invention, where the keyring adapter may be placed directly on the hub face, the brake discplaced on the key ring, with a simple cover ring capturing the brakedisc on the key ring.

The scope of the present invention further includes alternativeembodiments which similarly permit a “universal” or common rotor to befitted to existing hubs while flexibly being able to accommodatedifferent brake disc or rotor axial positions. For example, an innersurface of the key ring and/or a axial collar of the key ring may beprovided with internal threads configured to engage correspondingexternal threads on an axial surface of a hub. Coupled with a relativelythin locknut also threaded onto the hub's external threads, the key ringcould be rotated to a desired axial position and then locked into placeby tightening the locknut against an axial face of the key ring. Inaddition to providing essentially unlimited positioning variability inthe axial range of the overlapping threads, this arrangement may providea particularly axially-narrow brake disc mounting solution.

Alternatively, for existing designs in which the hub is not equippedwith external threads, an externally-threaded adapter base may besecured to the face of the hub using the hubs existing fasteners (e.g.,studs and nuts or bolts that screw into bores of the hub). A locknut andan internally-threaded intermediate key ring as the previous embodimentmay then be installed in the same manner on the adapter bases externalthreads.

A further embodiment may have the axial height adjustment capability ofthe present invention embodied in a manner that does not require eitherthe hub or an adapter base and the key ring to have correspondinginternal and external threads. For example, an adapter base withoutthreads may receive leadscrews that axially project toward the key ring,which in turn receive threaded collars. The collars may be configured toaxially receive the key ring, with the axial position of the key ringbeing adjustable by rotating the threaded collars along the leadscrewsuntil the desired axial position is reached. The threaded collars maythen be locked into place, for example by using jam nuts threaded ontothe remaining projecting threads of the leadscrews.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an oblique expanded view of a brake disc mounting arrangementin accordance with an embodiment of the present invention.

FIG. 1B is an oblique view of a key ring of the FIG. 1A embodiment.

FIG. 2A is an oblique view of the brake disc mounting arrangement of theFIG. 1A embodiment in a partially-assembled state.

FIG. 2B is an enlarged view of a key and brake disc slot of the FIG. 2Aembodiment.

FIG. 3 is an elevation view of the key and brake disc slot of the FIG.2B embodiment.

FIG. 4A is an oblique view of a cross-section of a prior art brake discmounting arrangement undergoing deformation during a braking event.

FIG. 4B is an oblique view of a cross-section of a brake disc mountingarrangement in accordance with an embodiment of the present inventionundergoing deformation during a braking event.

FIG. 5 is a cross-section view of a commercial vehicle wheel endarrangement.

FIG. 6 in an elevation side view of a brake disc and hub in accordancewith the present invention.

FIG. 7 is an oblique view of a brake disc showing multi-steppedkey-receiving slots in accordance with an embodiment of the presentinvention.

FIG. 8 is an oblique expanded view of the brake disc of FIG. 6 and acorresponding key ring.

FIG. 9 is an oblique expanded view of a universal brake disc mountingarrangement in accordance with an embodiment of the present invention.

FIG. 10A is a partial view of the hub region of a brake disc mountingarrangement in accordance with an embodiment of the present invention.

FIG. 10B is a comparative stress distribution chart illustrating stresslevels in the FIG. 10A brake disc mounting arrangement.

FIGS. 11A-11B are oblique and exploded views of an adjustable positionbrake disc arrangement in accordance with an embodiment of the presentinvention.

FIGS. 12A-12B are cross-section views of the brake disc arrangement ofFIGS. 11A-11B.

FIGS. 13A-13B are oblique and exploded views of another adjustableposition brake disc arrangement in accordance with an embodiment of thepresent invention.

FIGS. 14A-14C are cross-section views of the brake disc arrangement ofFIGS. 13A-13B.

FIG. 15 is an oblique exploded view of a further adjustable positionbrake disc arrangement in accordance with an embodiment of the presentinvention.

FIGS. 16A-16H are oblique and elevation views of the assembly process ofthe brake disc arrangement of FIG. 15.

FIGS. 17A-17B are cross-section views of the brake disc arrangement ofFIG. 15.

Common reference label numbers are used with common features in thefigures.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exploded view of a brake disc mounting embodiment 1including a rotating axle hub 2 located on an end of a vehicle axle (notillustrated), a brake disc 3, a ring 4 of wedge-shaped keys 4A connectedby inner-key webs 4B, a retaining ring 5 and brake disc retaining studs6A and corresponding retaining members, nuts 6B. The retaining ringalternatively may be separate washers, spring clips, or similar devicesfor each mounting location, as long as they do not interfere with thehub or rotor. The corresponding retaining members may be other than thenuts 6B, for example as clips or split pins, as long as the retainingmembers maintain a biasing force to bias the keys 4A against the axlehub 2.

The brake disc 3 at its radially inner circumference has acircumferential array of wedge-shaped slots 3A spaced and shaped tocooperate with corresponding ones of the keys 4A to fix the brake disc 3relative to the keys 4A in the circumferential direction. The keys 4A inFIG. 1A, shown in greater detail in FIG. 1B, include axial through-holes4C configured to receive and slide over the studs 6A to non-rotationallyfix the key ring 4, and hence the brake disc 3, to the rotating hub 2.In this embodiment, a tone ring 8 of a wheel speed detection system ispress-fit onto the hub 2; alternatively, the tone ring may be capturedbetween the hub 2 and the key ring 4 in an annular space between thestuds 6A and the hub's inner wheel bearing flange 2A.

In one example of a commercial vehicle wheel end arrangement, 10 studs6A may be arranged circumferentially about a circle with a radius of99.82 mm, with the key ring 4's through-holes 4C being laid out on acorresponding radius. The keys 4A may have a width in thecircumferential direction of approximately 28 mm and a radial height ofapproximately 18 mm. In FIG. 1A, the face of the axle hub which receivesthe brake disc is a substantially continuous planar surface, but thepresent invention is not limited to a continuous surface. Rather, theaxially outer face of the hub may be formed with multiple co-planarsurfaces which receive a brake disc and/or key ring adapter. Forexample, relatively small, flat surface areas may be provided around thebrake disc mounting studs in a plane perpendicular to the hub rotationaxis. The adapter need not be embodied as a complete ring.Alternatively, the adapter may be in the form of a plurality ofindividual adapter keys having small projections in the circumferentialdirection that axially support the brake disc, or sub-portions of aring, such as a plurality of pairs of keys connecting by a webtherebetween. Alternative approaches for securing the adapter are alsopossible, such as by the use of clamping members that cooperate with thehub to axially retain the mounting adapter, either at the keys or at atleast some of the inter-key webs.

FIG. 2A shows a view of the FIG. 1A brake disc mounting embodiment in apartially-assembled state, omitting the retaining ring 5 and retainingmembers 6B for clarity. The wedge-shaped slots 3A of the inner radialregion of the brake disc 3 have been moved axially over their respectivekeys 4A, which in turn are located on their respective brake discmounting studs 6A.

The geometry of an individual key and wedge-shaped slot pair is shown ingreater detail in FIG. 2B. The lateral sides 4D of the key 4A and thecorresponding lateral sides 3B of the wedge-shaped slot 3 are alignedrelatively close to lines that extend radially front the hub rotationaxis. With this arrangement, as the key 4A and the brake disc materialaround the wedge-shaped slot 3A expand and contract due to changes intemperature generated during and after a braking event, the lateralsides 3B and 4D may move across one another without binding. Preferablythe clearance between the lateral sides 3B and 4D is maintained as smallas practical in order to minimize the potential for differentialmovement in the circumferential direction, thereby minimizingopportunities for noise- and/or wear-generating impacts between theopposing lateral side contact faces, which may manifest as undesiredbrake disc vibrations.

Analysis of computer models of example embodiments over a range oftemperature and stress loadings expected during operation of commercialvehicle disc brakes has shown that the lateral side clearance may bereduced to 0.15 mm without encountering a temperature and stress loadingthat results in the brake disc slots being bound up on the keys.Computer modelling has also confirmed the surprising result that thereis a narrow range of key and slot side angles, relative to radial linesfrom the rotation axis, which provide significantly more evendistributions of stresses around the circumference of the brake diskduring a braking event than shallower or steeper angles. These improvedstress distributions were noted in the range of 12°-20°, and morepreferably in the range of 16°-18°. This feature of the presentinvention is discussed further in the context of FIGS. 10A and 10B,below.

FIG. 2B also shows a gap between the radially outer surface 4E of thekey 4 and the radially inner surface 3C of the wedge-shaped slot 3A,along with gaps between radiused regions 3D and 4F at the radially outercorners of the slot 3A and key 4A, respectively. In the examplecommercial vehicle wheel end arrangement, this radially outer gap may beapproximately 0.2-2.2 mm. In FIG. 2B the key radially outer surface 4Eis shown with a raised outer surface having a radius. This surfaceminimizes the gap to the brake disc in the central region of the key,but allows for slightly larger gaps in the laterally adjacent regionsnear the rounded corners 3D and 4F. Alternative outer surfaceconfigurations may be used, or the raised outer surface portion may beomitted from surface 4E.

The geometry of the corner radii and the width of the gaps are arrangedsuch that, across the range of thermal and stress loads expected to beencountered during the service life of the brake, the key's radiallyouter surface 4F does not contact the slot's radially inner surface 3C,or only lightly comes into contact with the surface in a manner thatdoes not apply significant loads to the inner surface 3C.

One of the features of the present invention is the design of thecontact surfaces between the keys and the wedge-shaped slots to avoidboth stress concentration regions and surface contact stresses highenough to deform the surfaces. Thus, the contact surfaces (whetherplanar or curved) are designed to provide sufficient contact surfacearea to maintain local stress levels below at least the plasticdeformation range during the life of the brake disc and the keys.Further, the use of relatively broad-radius corner curves substantiallyreduces stress concentration in both the keys' radially outer corners 4Fand the brake disc slots' corners 3D. In the example commercial vehiclewheel end arrangement, the keys' corners 4F may have a radius of 6.5 mm,and the slots' corners may have a radius of 8 mm.

The geometry of the inter-key webs 4B may also be optimized for a givenapplication. For example, where the inter-key webs 4B do not need to befull width in the radial direction in order to withstand the anticipatedstresses, portions of the webs may be omitted, such as scalloped regions4H, to both minimize weight and minimize ring-to-hub contact surfacearea and thereby decrease conductive heat transfer through the inter-keywebs to the hub. This arrangement may also reduce press requirements formanufacturing.

FIG. 3 shows a partial view of the key ring 4 and brake disc 3 from theradially inner region, looking radially outward. The bottom of FIG. 3shows the surface of the key ring 4 which abuts the face of the hub 2(not shown) when the key ring is in an installed position on the hub 2.In this embodiment, the brake disc slots 3A slide over the keys 4A untilthe brake disc abuts the inter-key webs 4B, followed by installation ofretaining ring 5 and retaining members 6B over the retaining studs 6A(retaining components not shown for clarity).

Preferably, the keys 4A have an axial height that results in an outerend 4G of the keys protruding slightly beyond the face of the brake discadjacent to the slots 3A. The protruding ends 4G are designed to receivethe retaining ring 5 in a manner that axially captures the brake disc 3between the inter-key webs 4B and the retaining ring 5 in a manner thatleaves the brake disc free to move axially over small distances toaccommodate axial forces during brake operation (for example, to be ableto move to center itself between opposing brake pads without inducingbending stresses in the brake disc that would otherwise be present ifthe brake disc was immovably mounted), as well as to allow for axialexpansion of the brake disc without the disc becoming fixed to the hub.In the example commercial vehicle wheel end arrangement, the axialthickness of the brake disc 3 in the regions adjacent to the slots 3Amay be 17.5 mm, with the keys 4A having an axial thickness of 18 mm,thereby providing a 0.5 mm range of axial motion for the floating brakedisc. In this example, the overall axial height of the key ring 4 isapproximately 29 mm, with the inter-key webs 4B being approximately 11mm thick. This inter-key web thickness provides enough material to givesufficient key ring stiffness and resistance to deformation when theretaining members 6B are torqued down, while avoiding excess thicknessthat unnecessarily increases the axial height of the vehicle wheel end.

The present invention is not limited to an arrangement in which theretaining fasteners cooperate with the axle hub (via the hub-mountedstuds or apertures in the hub) to capture the retaining ring and themounting adapter. For example, the retaining fasteners may be bolts thatthread into the holes in the mounting adapter keys, while the mountingadapter is separately retained on the axle hub via apertures in theinter-key webs through which pass the hub-mounted studs or fastenersthat engage the hub apertures.

Because the greatest physical and thermal stresses may be expected atthe keys (which must transfer braking forces from the brake disc to thehub via the retaining studs, and are the primary conductive heattransfer conduits between the brake disc and the hub), the material ofthe key ring 4 is preferably a high strength, high temperature tolerancematerial. More preferably, the material of the keys has a thermalexpansion coefficient similar to that of the brake disc material tominimize relative movement between the keys and the brake disc slotsduring braking events.

Preferably the keys are formed from a powdered metal material,especially preferably a powdered metal alloy having a composition ofFLC-4805-100HT per MPIF Standard 35 (0.5-0.7% C, 1.2-1.6% Ni, 1.1-1.4%Mo, 0.7-1.4% Cu, 0.3-0.5% Mn, balance Fe). The keys may be formed bycompression in a high pressure press in the conventional manner. For thebrake discs of a typical commercial vehicle, a 750 Ton press has provensufficient to produce key rings with the desired targeted materialdensities in the vicinity of 7 grams/cm³ in the preferred powdered metalalloy materials. As well known in the art, the operating parameters ofthe press and sintering operations will vary greatly depending on thespecific size, shape and desired material properties of the sinteredpowdered metal component (e.g., the targeted material densities of aspecific component). The key ring in the FIG. 1B embodiment was formedin a mold in a 750 Ton press, applying 6000 kN of compressive force whenthe powdered metal alloy material was at approximately 25° C., and theformed component was sintered at a temperature of 1120° C. Because theseparameters are variable and depend on the specific design beingproduced, and further because one of ordinary skill in the art can,without undue experimentation, vary the production process parameters toensure the resulting component meets the material property requirementsof a particular design, further discussion of the process parameters isomitted.

The key ring 4 is not limited to being a one-piece, integrally-formedcomponent. Alternatively, the key ring may be formed with inter-key webs4B or a complete base ring to which individual keys 4A are fixed. Thislatter arrangement permits targeted optimization of material costs andstrength, such as the potential use of keys 4A formed from ahigh-strength material while the remaining portions of the ring areformed from lower-strength, lower-cost material.

FIGS. 4A and 4B graphically illustrate another advantage of the presentinvention, the greatly increased uniformity in stress distributionwithin the rotor discs of a brake disc that result from thesubstantially more stiff construction of the present invention'sapproach to brake disc attachment.

FIG. 4A is an oblique view of a computer model of a cross-section of aprior art brake disc using a splined disc mounting approach of a largenumber of spring elements 7A and relatively long fasteners 7B holdingthe brake disc 8 directly to an axle hub (not illustrated). Theelongated fasteners 7B are prone to significant elastic deformationduring a braking event. The fasteners' deformation allows correspondinglocal elastic deformation of the brake disc 8, resulting in the brakedisc experiencing uneven stress distribution radiating away from theregion where the brake pads are applying forces to the disc frictionrings. In the FIG. 4A example, as the individual fasteners pass throughthe region in which the brake caliper presses the brake pads against thefriction surface of the brake disc 8 (in this figure, in the upper leftregion of the brake disc), the deformation in the brake disc is highest(up to 9.37 mm) at the outer radius of the disc, and is still more than6 mm at the inner radius in the brake pad region.

FIG. 4B shows how the rigid structure of the relatively broad keys andthe large contact surfaces between the keys and the brake disc slots ofthe present invention better resists elastic deformation at the brakedisc mounting region, and hence across the entire brake disc. This isvisible in the nearly-constant amount of deformation in the brake discaround its entire circumference, with this more even load bearingresulting in 11% lower peak deformation at the outer radius of the discfriction surface (8.306 mm vs. 9.375 mm), and an even greater 40%reduction in deformation at the brake disc's inner radius (3.69 mm vs.6.25 mm). The additional stability of the brake disc, particularly atthe inner region where the brake disc is attached to the hub, provides adisc mounting arrangement that is more durable and long-lived thanprevious mounting approaches.

In a further embodiment, the brake disc 3 and key ring 4 may be designedas parts of a “generic” brake disc system in which a single brake disc,or one of only a few such brake discs, having the present invention'sgap-driven key mounting arrangement is configured to cooperate with asuitable key ring adapter to replace application-specific brake discs.

FIG. 5 is a cross-section view of a typical commercial vehicle wheel endarrangement 10. Axle 11 supports a hub 2 via bearings 12. The hub 2 haswheel mounting studs 13 facing axially outward (in FIG. 5, toward theleft side of the figure), and on a rear or inner side receives a brakedisc 14 having rotor friction portion 14A and rotor hat portion 14B. Therotor is straddled in the known manner by a brake carrier and caliper(omitted for clarity) which is non-rotatably supported on a torque plate(aka anchor plate) 15 via a brake flange 16 fixed to the axle 11.

Important dimensions in any combination of these wheel end componentsinclude: the torque plate offset distance 17, i.e., the distance bywhich the torque plate 15 holding the brake carrier is axially offsetfrom the axle's brake flange 16; the flange offset distance 18, i.e.,the distance the axle's hub-locating surface (here, the axle bearingseat for the inner one of the hub bearings 12) to the axle's brakeflange 16; the hub offset 19, i.e., the distance from the hub's axiallocating surface (here, the opposite side of the inner hub bearing 12)to the face of the hub flange that receives a wheel; and the brake discoffset 20, i.e., the distance between the hub's wheel flange and thefriction surface of the brake disc rotor portion 14A. Regardless of themanufacturer(s) of these components, and specific combinations ofcomponents dictate where the brake disc 14 is located axially along theaxle.

The wheel end arrangement shown in FIG. 5 uses a brake disc 14 with arotor portion 14A that is connected to the inner face of the hub 2 viathe axial drum-shaped rotor hat 14B, but other hub configurations areknown, such as the hub shown in FIG. 6 having a drum-shaped section 21extending axially inward to the location of the rotor portion 14A tosupport the rotor.

In the FIG. 6 embodiment, the brake disc 3 is received by the key ring 4on the inner end of the hub drum-shaped portion 21. With knowledge aparticular combination of wheel end components (regardless ofmanufacturer), the final axial position of the rotor portion of thebrake disc may be readily determined. The thickness of the inter-keywebs 4B may then be set such that the friction surfaces of the rotor 3are axially positioned in the same location as the rotor portion 14A inFIG. 5.

The universality of the present invention's approach may be furtherextended, and the number of brake disc and key ring parts needed to bemaintained in inventory may be further reduced, by using brake discswith multiple key-to-brake disc contact surface heights, as shown inFIGS. 7-8.

While in the industry there are numerous possible combinations of wheelend components, as a practical matter the constraints on the availablespace for mounting components at a wheel end (e.g., limited space insidea wheel rim envelope, limitations from nearby adjacent components suchas knuckles and steering components) results in the range of brake discaxial locations being relatively limited, on the order of millimeters.In such applications, the present invention can provide a flexible brakedisc mounting solution that can accommodate several wheel end componentcombinations with only minimal number of “universal” brake discs and keyring adapters.

FIG. 7 shows a brake disc 33 with a plurality of wedge-shaped slots 33A,33B, 33C corresponding to the wedge-shaped slots 3A in FIG. 1. Unlikethe wedge-shaped slots 3A, the slots 33A, 33B, 33C are not open in theaxial direction, but instead have stepped regions 33D, 33E, 33F ofdifferent thicknesses. For example, the thicknesses of the steppedregions may be set with a 4 mm separation, enabling one brake disc 33 tocover applications over a broad 8 mm range of axial location needs. Thedesired axial brake disc offset may be obtained by, as shown in FIG. 8,by rotating during installation a key ring 34 having keys 34A configuredand spaced around the key ring to match groups of slot stepped regionshaving the same axial thickness (in this embodiment, a key correspondingto every third brake disc slot, corresponding to the three groups ofstepped regions with different axial thicknesses). This embodimentfurther shows an alternative key ring configuration, in which the keyring is secured to the hub by fasteners passing through apertures 34Cthat are on a radius smaller that the inner radius of the brake disc 33,with additional fasteners 35 being used to secure the keys 34A to theirrespective brake disc slots. This arrangement eliminates the need foruse of a separate brake disc retaining ring such as the retaining ring 5in the FIG. 1A embodiment. This alternative fixation arrangement is notlimited to this configuration, however. For example, the hub's fasteners(e.g., brake disc mounting studs or bolts) may pass through holes in thekeys corresponding to holes 4C in the FIG. 1A embodiment and throughholes in at least the brake disc slot stepped regions that are beingused to set the brake disc axial offset location.

Similarly, a “universal” brake disc may be provided with slot shelvesall having the same thickness, to be used with one of a plurality of keyrings having different key heights, as shown in FIG. 9. In thisembodiment, the brake disc 43 has wedge-shaped slots 43A of the sameaxial depth (and thus shelves of the same axial thickness), with the keyring 44 selected for use in the particular application having keys 44Ain corresponding locations about the key ring to position the brake disc43 at the desired axial offset position when the brake disc is installedon the key ring.

FIG. 9 shows a further feature of the present invention. Among the wheelend parameters that may vary between different manufacturers' wheel endconfigurations are the diameter of the axle and the diameter of the hubbearings on which the hub is mounted on the axle. In another variationon the present invention, a “universal” hub adapter 45 may be providedto provide a standardized interface on which the key ring 44 isreceived. The hub adapter may be produced in a limited number of sizeconfigurations that would cover a majority of hub models produced byvarious manufacturers, with the hub adapter dimensioned with an innerradius that would fit over various-diameter hub barrels whilemaintaining a standardized end face 45A to corresponding key rings 44.Advantageously the standardized end face 45 may include alignment slots45B configured receive corresponding alignment ribs 44B of die key ring44 to align these components and assist the brake disc mounting studs(not shown for clarity) as anti-rotation features.

An example of the extent of improvement in the brake disc stress levelspossible in the mounting arrangements of the present invention inprovided with the assistance of FIGS. 10A and 10B. FIG. 10A shows apartial view of the hub region of a brake disc mourning arrangementhaving ten retaining studs 6A, ten keys 4A, ten brake disc wedge-shapedslots 3A, and ten numbered radially-inward brake disc teeth 3E betweenthe slots 3A. At the top of FIG. 10A is a schematically illustratedbrake pad 46 symbolizing the location at which the brake pads interactwith the brake disc friction surfaces and generate braking forces dialare transferred via the brake disc, the key ring and retaining studs tothe hub 2 (not illustrated here for clarity).

FIG. 10B shows a comparative stress distribution bar graph, illustratingstress levels in the FIG. 10A brake disc mounting arrangement. As thebrake pads apply braking forces to the friction surfaces of the brakedisc, uneven force distribution patterns develop in the rotating brakedisc. This results from several factors, including localized deformationof the brake disc as one portion of the friction surface disc enters theregion clamped by the brake pads and another portion leaves the brakepad region.

The FIG. 10B graph shows example stress distributions in each of the tenbrake disc teeth in two brake disc examples, a brake disc havingparallel-sided (“straight”) teeth commonly found on so-called splinedbrake discs, and a brake disc having teeth with angled sides inaccordance with the present invention. In this embodiment the angledteeth sides are at an angle of 16°. The graph plots the relative amountof the stress borne by each of the brake disc teeth (x-axis) againsteach tooth position (y-axis). The upper bar at each tooth positionrepresents that tooth's share of the loading by the applied brakingforces in the case of the brake disc with straight-sided teeth. Thelower bars then represent share of the brake force loading of each toothin the FIG. 10A embodiment of the present invention.

FIG. 10B shows that a significantly better stress distribution wasobserved in the brake disc having present invention's radial tootharrangement as compared to a straight-tooth brake disc. In thiscomparison, the tooth in the FIG. 10A brake disc bearing the higheststress was loaded at a level that was substantially lower than thehighest-stress tooth in the straight-tooth brake disc: the FIG. 10Atooth 3 carried 14.9% of the brake force loading, as compared to thestraight-tooth brake disc's tooth 2 bearing 22.6% of the total load.Thus, the present invention provided a much more even circumferentialdistribution of braking forces, reducing maximum stresses toapproximately two-thirds of a prior art brake disc. This large decreasein stress level enables many design benefits because the components andthe materials being used do not have to be able withstand the muchhigher peak stresses seen in the prior art.

Additional embodiments of a “universal” brake disc mounting arrangementin accordance with the present invention are shown in FIGS. 11A-11B.

The first of the additional embodiments is shown in FIGS. 11A-11B and12A-12B. In this embodiment the axial position of the brake rotor 3 isreadily adjustable by the use of a threaded axial stop arrangement. Inthis embodiment of the arrangement, the hub 2 is provided with externalthreads 52. A corresponding locknut 54 is threaded onto the externalthreads 52 a predetermined distance (discussed further, below). The keyring in this embodiment takes the form of an adjustable intermediatering 104, having keys 4 on a face axially away from the hub 2, and aninternal thread 53 in a collar portion 55 which is configured to engagethe hub external thread 52. With this arrangement, the axial position ofthe brake rotor 3 may be set to any location within the range of threadoverlap by rotating the adjustable intermediate ring 104 to the desireddepth, and then rotating the locknut 54 against the hub-side face of thecollar 55 to lock the position of the ring 104. The brake rotor 3 maythen be secured on the keys 4 with retaining ring 5 and retainingmembers, in this embodiment hex bolts 6C which thread into correspondinginternal threads in key holes 4C.

A cross-section-view of the FIG. 11A embodiment is shown in FIG. 12A,with the axial height of the collar portion 55 of the intermediate ring104 spaced as a desired depth above the shoulder on hub 2 at the end ofits external threads 52. As shown in the enlarged portion of FIG. 12A inFIG. 12B, as in the FIG. 3 embodiment preferably the axial height of thekeys 4A are taller than that of the adjacent portions of the brake disc3, such that there is a protruding key end 4G that receives theretaining ring 5 and thereby ensures the brake rotor 3 remains free toaxially float between the hub 2 and the retaining ring 5.

Another embodiment of the present invention is illustrated in FIGS.13A-13B and 14A-14C. As with the embodiment in FIGS. 11A-11B and12A-12B, large-diameter threaded sections and a large locking nut areused to set a desired axial position of the brake rotor 3. A differencein this and the previous embodiment is that this embodiment provides forready adaptation of a common brake rotor 3 to already-existing hubdesigns (either as a back-fit kit or in a newly-manufactured brake) byuse of an adapter base 56 sized to slide over existing brake discretaining studs 6A and be retaining against the face of the hub 2 byretaining members 6B. The adapter base 56 carries the external threadson which are threaded the locknut 54 and the collar 55 of theintermediate ring 104. The remaining assembly of the brake then proceedsas in the previous embodiment, with the locknut 54 and collar portion 55being threaded onto the adapter base 56 and axially locked into positionagainst one another, and location of the brake rotor 3 on the keys 4A,retained by retaining ring 5 and hex bolls 6C. With this arrangement, aconventional unthreaded hub 2 may be adapted without additionalmachining or wholesale hub replacement to allow use of a common brakerotor 3.

A cross-section-view of the FIG. 13A embodiment is shown in FIG. 14A,with additional details shown in the enlarged portions in FIGS. 14B-14C.FIG. 14B shows the securing of the adapter base 56, with its externalthreads 52, to the hub 2 by studs 6A and nuts 6B. Because the adapterbase 56 fasteners 6B may be installed prior to installation of thelocknut 54 and intermediate ring 104, a technician has free access totorque the fasteners 6B to a prescribed lightness. This view also showsthe collar 55 of the intermediate ring 104 having been secured againstrotation out of its axial position by thread friction generated bytightening of the locknut 54 against the axial face of the collar.

FIG. 14C shows the location of the brake rotor 3 on the keys 4A of theintermediate ring 104 in the same manner as in the previous embodiment,with the protruding face 4G of the key 4A holding the retaining ringaxially outward such that the brake rotor 3 remains able to axiallyfloat.

FIGS. 15, 16A-16H and 17A-17B show a further embodiment of anarrangement of the present invention that is readily adaptable to use onexisting hub designs.

In the FIG. 15 embodiment, the adapter base 56 is also retained on thehub's studs 6A on an axial face of the hub 2, but the intermediate ring104 is not held directly on the axial face of the adapter base 56.Instead, a plurality of leadscrews 106A protrude axially outward fromthe adapter base, and threaded collars 106C located are located on theleadscrews 106A between the adapter base and the intermediate ring 104.The axial position of the intermediate ring 104, and hence the brakerotor 3, is set by rotation of the threaded collars 106C on theirrespective leadscrews 106A. In this embodiment, the intermediate ring104 does not have an axially-extending collar portion 55, whichfacilitates positioning of the brake rotor 3 axially closer to hub 2.

The intermediate ring in this embodiment is guided in thecircumferential direction by pins 58 installed on the adapter base 56 inFIG. 16A and the leadscrews 106A, which alternate with one another andtogether cooperate to sustain the loads applied by the brake rotor 3 inthe circumferential direction during a braking event. As shown in FIG.16B, the heads of the leadscrews 106A are captured between the adapterbase 56 and the hub 2 when the adapter base 56 is passed over the hubstuds 6A and secured to the hub 2 by fasteners 6B. FIG. 16C shows thepositioning of the threaded collars 106C on the leadscrews 106A prior toinstallation of the intermediate ring 104. Once the intermediate ring104 is located over the adapter base and the threaded collars arerotated to obtain the desired axial position of the intermediate ring104, the jam nuts 106B shown in FIG. 16D are tightened onto the ends ofthe lead screws 106A which protrude through the threaded collars 106C,thereby locking the axial position of the threaded collars 106C and theintermediate ring 104 relative to the adapter based 56 and hub 2.

Following the tightening of the jam nuts 106B, the brake rotor 3, suchas the envisioned “universal” or common brake rotor shown in FIG. 16E,may be installed on the intermediate ring 104 and axially retained byretaining ring 5 and hex bolts 6C, as shown in FIGS. 16F-16G. Anadvantage of this embodiment is illustrated in FIG. 17, which shows anelevation view of this embodiment of the present invention lookingaxially toward the hub 2. In this arrangement, the brake rotor 3 andintermediate ring 104 may be sized such that all of the fasteners may bereadily accessed without interference from immediately radially-adjacentinterferences. This permits the components of the brake mountingarrangement to be assembled and disassembled, partially or entirely, inany order required to service the brake. For example, if a stud 6A needsto be replaced on a brake whose intermediate ring 104 has already beenadjusted with the threaded collars 106C to obtain the desired axialposition of brake rotor 3, the fasteners 6B may be removed so that theentire assembly of the adapter base 56, intermediate ring 104 and brakerotor 3 may be removed as a module from the hub studs 6A. Followingrepair of the damaged stud 6A, the entire module may be reinstalled in asimple and cost-effective manner.

FIGS. 17A-17B show cross-section views of the FIGS. 15 and 16A-16Hembodiment. In particular, FIG. 17 is an enlarged view of thearrangements of one of the leadscrews 106A. Here, the head of theleadscrew 106A is press-fitted into a recess of the adapter base 56. Thethreaded collar 106C is installed on the threads of the leadscrew 106Ato the desired axial height above the axially-outer face of the adapterbase 56, and receives the intermediate ring 104. A jam nut 106B locksthe threaded collar 106C at the desired axial position. A counter borein the intermediate ring 104 provides sufficient radial clearance topermit a tool, such as a socket, to be used to tighten the jam nut.Radial clearance is also provided between the end of the leadscrew 106Aprotruding up to retaining ring 5. The retaining ring 5 is separatelyretained on the keys of the intermediate ring 104 by the fasteners 6C,one of which is shown out of the plane of the FIG. 17B cross-section.

A method of assembly of the brake disc arrangement of FIG. 15 generallyfollows the assembly shown in FIGS. 16A-16H. One of ordinary skill inthe art will recognize that several of the acts in the method may beperformed in a different order. For example, the adjustment of the axialposition of the threaded collars 106C on the leadscrews 106A, followedby tightening of the jam nuts 106B, may be performed after the brakedisc arrangement is in an installed position on an axle hub, such thatthe axial position of the brake rotor 3 may be fine-tuned to match theactual axial position of the brake's caliper and brake pads.

The foregoing embodiment of the present invention is not limited toarrangements in which the brake disc mounting adapter is retained on thethreaded collars separate from the retention of the retaining ring onthe brake disc mounting adapter. For example, the retaining fastenersmay be configured to both retain the retaining ring and serve thefunction of the jam nuts to axially fix the position of the threadedcollars on the leadscrews.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. For example, an axle hubmay be provided with key ring adapter-receiving surfaces that areaxially inboard of the outboard-most face of the hub (i.e., some portionof the hub may protrude through the center of the key ring), as long asthe key ring and brake disc are mountable on the hub. Sincemodifications of the disclosed embodiments incorporating the spirit andsubstance of the invention may occur to persons skilled in the art, theinvention should be construed to include everything within the scope ofthe appended claims and equivalents thereof.

LISTING OF REFERENCE LABELS

-   -   1 brake disc mounting arrangement    -   2 axle hub    -   3 brake disc    -   3A wedge-shaped slot    -   3B lateral side    -   3C radially inner surface    -   3D radiused region    -   3E brake disc teeth    -   4 key ring    -   4A key    -   4B inter-key web    -   4C hole    -   4D lateral side    -   4E radially outer surface    -   4F radiused region    -   4G protruding end    -   4H scalloped region    -   5 retaining ring    -   6A retaining stud    -   6B retaining member    -   7A spring element    -   7B fastener    -   8 brake disc    -   10 wheel end arrangement    -   11 axle    -   12 bearing    -   13 wheel mounting stud    -   14 brake disc    -   14A rotor portion    -   14B rotor hat    -   15 torque plate    -   16 brake flange    -   17 torque plate offset    -   18 flange offset    -   19 hub offset    -   20 brake disc offset    -   21 hub drum-shaped portion    -   33 brake disc    -   33A, 33B, 33C wedge-shaped slot    -   33D, 33E, 33F shell    -   34 key ring    -   34A key    -   34C hole    -   35 fastener    -   43 brake disc    -   43A wedge-shaped slot    -   44 key ring    -   44A key    -   44B alignment rib    -   45 hub adapter    -   45A end face    -   45B alignment slot    -   46 brake pad    -   52 external threads    -   53 internal threads    -   54 locknut    -   55 collar    -   56 adapter base    -   58 pin    -   104 adjustable intermediate ring    -   106A leadscrew    -   106B jam nut    -   106C threaded collar

What is claimed is:
 1. A brake disc mounting arrangement, comprising: anaxle hub having a rotation axis and at least one of hub-mountedfasteners and fastener-receiving apertures; a brake disc mountingadapter configured to cooperate with the at least one of hub-mountedfasteners and fastener-receiving apertures to locate the brake discmounting adapter on the axle hub, the brake disc mounting adapterincluding a plurality of wedge-shaped brake disc mounting keys; a brakedisc having a plurality of wedge-shaped slots circumferentially around aradially inner region of the brake disc, the wedge-shaped slots beingconfigured to be received on corresponding ones of the brake discmounting adapter keys when the brake disc is in an installed position onthe axle hub; a brake disc retainer; and retaining fasteners configuredto cooperate with the brake disc retainer and at least one of the brakedisc mounting adapter and the at least one of hub-mounted fasteners andfastener-receiving apertures to axially retain the brake disc on thebrake disc mounting adapter, wherein the brake disc mounting adapter isa key ring with the plurality of wedge-shaped brake disc mounting keysconnected by inter-key webs between adjacent ones of the plurality ofkeys, all of the inter-key webs being located in a plane perpendicularto the rotation axis at a hub-facing side of the brake disc, and theplurality of wedge-shaped brake disc mounting keys have an axialthickness which extends across a central region of respective ones ofthe plurality of brake disc wedge-shaped slots.
 2. The brake discmounting arrangement of claim 1, wherein the at least one of hub-mountedfasteners and fastener-receiving apertures are studs, and each of theplurality of keys includes an aperture configured to receive one of thestuds when the key ring is in an installed position on the axle hub. 3.The brake disc mounting arrangement of claim 2, wherein the retainingfasteners are nuts configured to thread onto the studs, and when in aninstalled position on the studs, the nuts bias the brake disc mountingadapter against at least one brake disc mounting surface of the hub. 4.The brake disc mounting arrangement of claim 3, wherein an axialthickness of the plurality of keys is greater than an axial thickness ofthe brake disc between the plurality of slots, and the brake disc isaxially displaceable between the brake disc retainer and the key ringinter-key webs.
 5. The brake disc mounting arrangement of claim 4,wherein the plurality of keys and the plurality of wedge-shaped slotsare configured to expand and contract in response to temperature changesin a manner such that the plurality of keys do not bind the brake discagainst radial expansion and contraction.
 6. The brake disc mountingarrangement of claim 5, wherein opposing circumferentially lateral facesof the plurality of keys and the plurality of wedge-shaped slots arealigned substantially parallel to radii extending outward from arotation axis of the brake disc.
 7. The brake disc mounting arrangementof claim 6, wherein the opposing circumferentially lateral faces arearranged at an angle relative to the radii of 12° to 20°.
 8. The brakedisc mounting arrangement of claim 7, wherein the angle is 16° to 18°.9. The brake disc mounting arrangement of claim 5, wherein opposingcircumferentially lateral faces of the plurality of keys and theplurality of wedge-shaped slots are aligned relative to radii extendingoutward from a rotation axis of the brake disc such that a ratio of aloading on one of the plurality of keys having a highest loading duringa braking event compared to a loading on another one of the plurality ofkeys having a lowest loading during a braking event is less than 2:1.10. The brake disc mounting arrangement of claim 2, wherein theretaining fasteners are nuts with flanged sections configured to threadonto the studs, and when in an installed position on the studs, the nutsbias the brake disc mounting adapter against at least one brake discmounting surface of the hub.
 11. The brake disc mounting arrangement ofclaim 1, wherein an axial thickness of the plurality of keys is greaterthan an axial thickness of the brake disc teeth, and the brake disc isaxially displaceable between the brake disc retainer and the key ringinter-key webs.
 12. The brake disc mounting arrangement of claim 11,wherein opposing circumferentially lateral faces of the plurality ofkeys and the plurality of wedge-shaped slots are aligned relative toradii extending outward from a rotation axis of the brake disc such thata loading on each of the plurality of keys during a braking event isbetween 4% and 17% of the total load on all of the keys.
 13. The brakedisc mounting arrangement of claim 1, wherein a ratio of a loading onone of the plurality of keys having a highest loading during a brakingevent compared to a loading on another one of the plurality of keyshaving a lowest loading during a braking event is less than 2:1.
 14. Thebrake disc mounting arrangement of claim 1, wherein no shim or springhardware is present between opposing circumferentially lateral faces ofthe plurality of keys and the plurality of wedge-shaped slots.
 15. Thebrake disc mounting arrangement of claim 1, wherein a loading on each ofthe plurality of keys during a braking event is between 4% and 17% ofthe total load on all of the keys.
 16. A brake disc mountingarrangement, comprising: a brake disc mounting adapter configured to belocated on an axle hub and to cooperate with at least one of hub-mountedfasteners and fastener-receiving apertures to locate the brake discmounting adapter on the axle hub, the brake disc mounting adapterincluding a plurality of wedge-shaped brake disc mounting keys; a brakedisc having a plurality of wedge-shaped slots circumferentially around aradially inner region of the brake disc, the wedge-shaped slots beingconfigured to be received on corresponding ones of the brake discmounting adapter keys when the brake disc is in an installed position onthe axle hub; a brake disc retainer; and retaining fasteners configuredto cooperate with the brake disc retainer and at least one of the brakedisc mounting adapter and the at least one of hub-mounted fasteners andfastener-receiving apertures to axially retain the brake disc on thebrake disc mounting adapter, wherein the brake disc mounting adapter isa key ring with the plurality of wedge-shaped brake disc mounting keysconnected by inter-key webs between adjacent ones of the plurality ofkeys, all of the inter-key webs being located axially in a planeperpendicular to the rotation axis, the plane being at a hub-facing sideof the brake disc, and the plurality of wedge-shaped brake disc mountingkeys have an axial thickness which extends across a central region ofrespective ones of the plurality of brake disc wedge-shaped slots. 17.The brake disc mounting arrangement of claim 16, wherein the at leastone of hub-mounted fasteners and fastener-receiving apertures are studs,and each of the plurality of keys includes an aperture configured toreceive one of the studs when the key ring is in an installed positionon the axle hub.
 18. The brake disc mounting arrangement of claim 17,wherein the retaining fasteners are nuts configured to thread onto thestuds, and when in an installed position on the studs, the nuts bias thebrake disc mounting adapter against at least one brake disc mountingsurface of the hub.
 19. The brake disc mounting arrangement of claim 18,wherein an axial thickness of the plurality of keys is greater than anaxial thickness of the brake disc between the plurality of slots, andthe brake disc is axially displaceable between the brake disc retainerand the key ring inter-key webs.
 20. The brake disc mounting arrangementof claim 19, wherein the plurality of keys and the plurality ofwedge-shaped slots are configured to expand and contract in response totemperature changes in a manner such that the plurality of keys does notbind the brake disc against radial expansion and contraction.
 21. Thebrake disc mounting arrangement of claim 20, wherein opposingcircumferentially lateral faces of the plurality of keys and theplurality of wedge-shaped slots are aligned substantially parallel toradii extending outward from a rotation axis of the brake disc.
 22. Thebrake disc mounting arrangement of claim 20, wherein opposingcircumferentially lateral faces of the plurality of keys and theplurality of wedge-shaped slots are aligned relative to radii extendingoutward from a rotation axis of the brake disc such that a loading oneach of the plurality of keys during a braking event is between 4% and17% of the total load on all of the keys.
 23. The brake disc mountingarrangement of claim 16, wherein the retaining fasteners are boltsconfigured to thread into apertures in the brake disc mounting adapterkeys, the brake disc mounting adapter inter-key webs include aperturesconfigured to receive the at least one of hub-mounted fasteners andfasteners configured to be received in the fastener-receiving aperturesof the axle hub, and when in an installed position inter-key webs arebiased against at least one brake disc mounting surface of the hub. 24.The brake disc mounting arrangement of claim 23, wherein an axialthickness of the plurality of keys is greater than an axial thickness ofthe brake disc teeth, and the brake disc is axially displaceable betweenthe brake disc retainer and the key ring inter-key webs.
 25. The brakedisc mounting arrangement of claim 24, wherein the opposingcircumferentially lateral faces are arranged at an angle relative to theradii of 12° to 20°.
 26. The brake disc mounting arrangement of claim25, wherein the angle is 16° to 18°.
 27. The brake disc mountingarrangement of claim 16, wherein a ratio of a loading on one of theplurality of keys having a highest loading during a braking eventcompared to a loading on another one of the plurality of keys having alowest loading during a braking event is less than 2:1.
 28. The brakedisc mounting arrangement of claim 16, wherein no shim or springhardware is present between opposing circumferentially lateral faces ofthe plurality of keys and the plurality of wedge-shaped slots.
 29. Thebrake disc mounting arrangement of claim 16, wherein a loading on eachof the plurality of keys during a braking event is between 4% and 17% ofthe total load on all of the keys.